The present invention relates to digital copiers and multifunction peripherals (MFPs) and, more particularly, to copying techniques for improving the performance of a copier or MFP performing special document construction operations.
Digital photocopiers and multifunction peripherals (MFPs) (a single device that can function as a printer, a scanner, a facsimile machine, and a photocopier) (hereinafter, collectively, a “copier”) can perform a number of special document construction operations. One special document construction operation is “auto-sizing” in which an original image is reproduced at a scale proportioned to fit the copy on a sheet of copy paper or other copy medium of an arbitrarily selected size. Another special copying function is “auto-cloning” where the copier produces several images of a “small” original image arrayed on a sheet of copy medium. For example, it may be desired to produce several copies of a business card on a single sheet of copy medium.
An initial step in auto-sizing or auto-cloning is to establish the size of the original document or the original image (collectively referred to herein as the “original”), as appropriate for the operation. Typically, the size of the original is determined from scan data statistics accumulated as a sensor array is moved relative to the original. The extreme positions of sensors in the array detecting putative pixels of the original are typically accumulated for establishing one set of boundaries of the original. The number of scan lines intervening between the initial and final detection of supposed pixels of the original is used in determining the second set of boundaries. The size of the original is typically determined from statistical inferences from the scan data to avoid falsely identifying dust or smudges on the platen as a document edge and to account for the likelihood that the edges of the original are not square with the sensor array of the scanner.
Typically, size determination is performed with a low resolution pre-scan where only a subset of the sensors and scan lines of a full resolution scan are read and analyzed. The low resolution scan can be performed quickly, provides adequate information to estimate the boundaries of the original with sufficient accuracy, and is computationally less expensive than a full resolution scan. For auto-sizing, a processor then determines the zoom (either magnification or reduction) required to scale at least one of the width and length of the original to fit the size of the selected copy medium. In the case of auto-cloning, the processor determines the number and arrangement of full scale copies of the original that will fit on the copy medium. After the dimensions of the original have been determined, the original is scanned a second time at full resolution. The data from the full resolution scan is processed and the image is printed. While the method produces good results, repeated scanning is time consuming, complicates the copier firmware, increases the cycling of the scanner mechanism, and requires duplication of some of the control software which increases the amount of memory required for the software.
What is desired, therefore, is a technique for determining the size of an original that reduces the complexity of the copier and the time required to perform the special document construction operations.